The proposed research is a developmental investigation of precategorical acoustic storage (PAS). Studies employing a stimulus suffix to selectively lower recall of the last serial positions have been taken as support of a fast-decaying auditory sensory store that is sensitive to variations in input and may be confined to speech sounds. Words and vowels, but not consonants, can enter this store. Other studies using backward masking of tone recognition have failed to find such similarity effects and support a sensory store which includes non- speech sounds. A series of tests is proposed to distinguish these two models. In the stimulus suffix paradigm Ss hear and recall in serial order lists of words, vowels, or consonants. Control recall, signalled by a tone, is compared with recall cued by a final not-to-be recalled item, a stimulus suffix. A differential recall decrement for the last test item(s) after presentation of a stimulus suffix, a suffix effect, is taken as support for PAS. Since items in PAS are replaced by later entries, PAS representation of the final test item is available to assist recall only in the control condition; it is replaced by the stimulus suffix and recall of the final test item is therefore lowered. Failure to find a suffix effect, as with consonants, suggests that these items never entered PAS in the first place. The proposed research will use the stimulus suffix paradigm to investigate (1) the effect of a stimulus suffix on probed recall; (2) PAS representation of tones; (3) PAS representation of vowels and consonants in children; and (4) the development of the role of S's own voice in recall. The results of these studies will have theoretical implications for the development of auditory sensory memory and for speech perception as well.